The present invention is directed to systems and methods for heating and then cooling contents of flexible containers.
Many foodstuffs today, such as tomato paste, orange juice, crushed pineapple and diced tomatoes, are cooked and filled hot into flexible bags. The containers with the heated product (foodstuffs) must then be cooled for subsequent handling and storage.
An example of a system of the prior art for cooling contents of flexible bags is shown in FIG. 1 generally at 70. Referring thereto, the bags 72 enter the open-plastic belt conveyor 74 at one end into a first cooling station as shown generally at 76. Station 76 is shown in isolation in FIG. 2. The bag 72 is in a bath 78 of cooling water up to about its mid point. Overhead sprayers 80 spray cooling water on the tops of the bags 72. The bag 72 is conveyed by the mechanical action of the conveyor 74 to a gate 82 at the forward end of the station.
The gate 82 is formed by three stacked, upwardly rolling rollers 84, 86, 88. The actions of the conveyor 74 and the rollers 84, 86, 88 cause the bag 72 to rotate or turn over, as shown by arrow 90, about an axis generally perpendicular to the travel direction of the conveyor 74 to thereby partially mix the bag contents and to expose the bottom surface of the bag to the cooling water from the sprayers 80. The gate 82 is then pivoted down as shown by arrow 92, and the bags 72 are conveyed together to the next station for a subsequent cooling process, and so forth through the twelve or so stations.
There are a number of problems with the prior art system 70. One is that the overall process of system 70 is slow. It takes about forty minutes to cool the contents of the bag 72 from two hundred degrees down to below one hundred and twenty degrees Fahrenheit. Another problem is that the bags 72, and particularly when they are underfilled, occasionally get caught in the rollers 84, 86, 88 and break, spilling their contents. A further disadvantage of the prior art system 70 is that it occupies a large amount of floor space since it is approximately seventy feet long.
Other systems for cooling or heating the contents of flexible containers are shown in the following U.S. patents: U.S. Pat. No. 4,384,463 (Rica et al.), U.S. Pat. No. 5,009,150 (Andersen) and U.S. Pat. No. 5,370,174 (Silverstrini et al.). The contents of each of these patents and all other patents mentioned in this disclosure are hereby incorporated by reference in their entireties.
The present invention is directed to providing an efficient means for cooling (and/or heating) contents of flexible containers or bags. The bags with their hot contents are dropped into an infeed end of a trough containing cooling water. The bags are advanced from one station to the next in the trough by the periodic actuation of a fluid jet conveyor at the inlet end of the trough. After the bags are advanced to their respective next stations the fluid jet conveyor is turned off and the fluid nozzle system is turned on.
The fluid nozzle system includes a first series of nozzles on one side of the trough and directed into the trough and a second series of nozzles on the other side of the trough and similarly directed into the trough. The first series of nozzles are disposed in a horizontal plane spaced about four inches above the horizontal plane of the second series of nozzles. Thus, when the bag reaches the next station and the nozzle system is turned on, the water from about the five or so nozzles of the first series impinge against the adjacent side of the bag about two inches above the midline of the bag, and the water from the five or so nozzles of the second series impinge on the opposite side of the bag, about two inches below the midline of the bag.
The two sets of opposing and offset nozzles have two actions on the bag. First, they impinge and push in on the side of the bag, about twelve inches, for example, on each side. This xe2x80x9cmassagingxe2x80x9d action causes the central contents of the bag to move away from the center of the bag and towards the side of the bag thereby promoting the transfer of heat from the central contents of the bag to the cooling water at the surface of the bag. Second, they cause the bags to rotate about an axis generally parallel to the axis of the trough. This rotation motion in the bath of cool water in the trough also assists in the cooling of the bag""s contents. It is additionally within the scope of the invention to orient the nozzles so that the bag is rotated in a clockwise direction at one station and an opposite counterclockwise direction at a next station in the trough.
The bags generally abut one another end-to-end as they travel from station to station in the trough of the present system, and no gates or other structures separates them from the adjacent bags. The movement of the bags into, along and out of the trough is now described with respective bags in the three active stations in the trough and one in the ramped station (xe2x80x9cdead zonexe2x80x9d) at the exit end of the trough and with the offset nozzle system on. A detector at an infeed station above the trough input end detects the arrival of a hot filled bag. When this is detected the flow of the cooling water is switched from the offset nozzle system to the fluid jet conveyor and the first extraction conveyor is turned on. The bag at the ramped station is pushed onto the first extraction conveyor and conveyed away on it. The three bags in the trough move to their respective next stations by the action of the fluid jet conveyor. A detector generally at the outlet end of the extraction conveyor detects the arrival of the extraction bag and turns the first extraction conveyor off.
The first infeed station is then empty, and the hot filled bag detected by the infeed station detector slides down into the first infeed station. Thus, bags are now in the three active stations and in the ramped station. The bag at the ramped station advantageously acts as a plug or a soft gate, blocking the further advancement of the bags relative to the trough. The infeed station detector detects that no hot filled bag is at or nearly at the infeed station, and causes the cooling water to switch and flow to the nozzle system and not the fluid jet conveyor. The three bags in the three active stations are thereby massaged and rotated. When the infeed station detector detects the arrival of another hot filled bag, the process starts again.
A centrifugal pump pumps the cooling (or heating) fluid (water) from a cooling tower to a butterfly valve which directs the fluid flow to either the fluid nozzle system or the fluid jet conveyor. A bleed tube at the exposed eye of the impeller bleeds air out of the pump. The xe2x80x9cexposed eyexe2x80x9d is defined when the impeller center can be seen when looking down the suction line in the direction of liquid flow. U.S. Pat. No. 4,981,413 calls it the xe2x80x9ccenter of the pump impeller.xe2x80x9d (In contrast, see U.S. Pat. No. 3,575,521.) A low pressure check valve prevents air from being sucked into the pump through the bleed tube. Bleeding the pockets of air in the pump prevents the pump from losing its prime.
This pump arrangement invention, in addition to being used in the present heating/cooling environment, can be used aboard ships where the pump suction may become exposed in a rolling sea. It can be used generally in any application where the supply level is difficult to control and the pump loses its prime when air gets into the suction line.
An exemplary method for retrofitting such a pump in accordance with the present invention first disassembles the suction line from the pump. The bleed assembly is then attached to the pump. If the pump has a threaded housing, a threaded style bleeder is preferably used and screwed into place. On the other hand, if the pump has a flange face then a flanged bleeder or a threaded bleeder with a flange adapter can be used. Next, the bleeder line is extended to be as close as possible without actually touching the impeller. The suction line is then reattached (replumbing to shorten the suction line will probably be needed due to the space occupied by the bleeder). The outlet from the check valve to a drain may need to be plumbed. The bleed assembly""s operation is then checked by starting the pump, introducing air into the pump so that it loses its prime, stopping air introduction and making sure the pump xe2x80x9cburpsxe2x80x9d the air bubble through the bleeder and regains its prime.
Instead of cooling the contents of a flexible bag, it is also within the scope of the invention to heat the bag contents. More specifically, a large flexible bag is filled with unsterile product. The bag is sealed (or otherwise closed), and the (sealed) bag is loaded into a trough similar to that in the above-described cooling invention system. However, hot water is used instead of cool or cold water for both the fluid jet conveyor and the fluid nozzle system. The hot water from the nozzles impinges on opposite sides of the bag, massaging it and moving its central contents towards the surface or skin of the bag. The bag is also rotated. The heating is done quickly before the bag contents turn to mush, as would happen if the slower prior art system 70 used ambient product and hot water. Cooling can be performed, and the bags can then be boxed, providing a very economical replacement for cans. Small bags at a slow production rate can be handpacked in boxes. However, at faster rates and/or larger bags, automatic case packers, such as are currently available from FMC, Hayssen and Scholle, can be used.
Also disclosed herein is a novel nozzle assembly useful in the heating and cooling systems of this invention for heating or cooling contents of flexible containers and in other applications where a focused fluid flow is desirable as would be apparent to those skilled in the art. The nozzle assembly includes a nozzle unit, a first sleeve, a second sleeve and a clamp. The nozzle unit has an aft collar and an inner fluid contact surface. The surface tapers gradually to increase the velocity of fluid flowing therethrough about ten fold. Additionally, the elastomeric lining of the inner surface acts like an interior xe2x80x9cskinxe2x80x9d preventing turbulence from feeding back or building up on itself and thereby increasing the fluid power delivered by the nozzle assembly. The first sleeve has a first rear fitting, and the second sleeve has a second forward fitting. The clamp encircles the first and second fittings, holding them together with the collar sandwiched between them.
Accordingly, another way to define the present invention is that the shape and movement of the flexible bags are carefully controlled to maximize the heat transfer to the contents of the bags to quickly, efficiently and thoroughly heat or cool the contents. This is preferably done using water jets, but other means such as mechanical means including rollers, as would be apparent to those skilled in the art from this disclosure are also included herein. One way to adjust the shape and movement is to massage or otherwise manipulate the bags to move the central contents of the products therein towards the bag surface or skin. This can be done by opposing but offset forces on the bag. The action of the massaging (or offset forces) can also be done with a force on the bags causing them to rotate, preferably in a bath of heating or cooling fluid.
A further definition of the invention is the use of the heating or cooling fluid (e.g., liquid and specifically water) as the heat transfer medium for heating or cooling the contents of the flexible containers and also as the means for changing the shape and/or movement of the flexible containers to improve the heat transfer to their contents. The fluid thereby serves two functions. The fluid additionally can serve as the motive force (a third function) for moving the containers from one work station to the next.
The invention can thus be used to heat and/or cool contents of flexible containers. One embodiment fills the bags with hot product, closes the bags and then cools them pursuant to this invention. Another embodiment fills the bags with product at a cold or ambient temperature, closes the bags and then heats them pursuant to this invention. And a preferred way to close them is to seal them shut. The bags with heated product can then be cooled using a system of this invention. Alternatively, they can be cooled by other means as would be apparent to those skilled in the art.
Other objects and advantages of the present invention will become more apparent to those persons having ordinary skill in the art to which the present invention pertains from the foregoing description taken in conjunction with the accompanying drawings.